[AZ-Observing] How many comets?

  • From: Brian Skiff <Brian.Skiff@xxxxxxxxxx>
  • To: amastro@xxxxxxxxxxxxxxx, az-observing@xxxxxxxxxxxxx
  • Date: Mon, 19 Jan 2004 21:50:25 -0700 (MST)

     I was asked a few times in the past week, following the announcement
of P/2004 A1, how many comets I have.  My answer is either "I don't know" or
"some".  Here's why.  The list below shows comets that have my name attached,
with as-yet-unnamed 2004 A1 shown for completeness, along with a gloss on the
discovery circumstances.  The IAU Circulars are the journal-of-record for
comets, and the discovery announcements are available on-line at the URLs
shown for each object.

140P/1983 C1 (Bowell-Skiff)   found by Ted Bowell on Pluto Camera plates taken
                              by me; Saturn-family comet

D/1977 C1 (Skiff-Kosai)       found by me on a Palomar Schmidt plate taken by
                              Charlie Kowal, identified as asteroid previously
                              reported by Hiroki Kosai (Kiso Schmidt);
                              now considered lost Jupiter-family comet

114P/1986 Y1 (Wiseman-Skiff)  found by Jennifer Wiseman on Pluto Camera plates
                              taken by me; Jupiter-family comet

C/1999 J2 (Skiff)             found on LONEOS images; large perihelion distance
                              with hyperbolic orbit

C/1999 U4 (Catalina-Skiff)    reported as a comet, but found the day prior
                              by Tim Spahr at Catalina and reported only as
                              having unusual motion by him; hyperbolic orbit

P/2000 S1 (Skiff)             found on LONEOS images; Saturn-family comet

C/2000 Y2 (Skiff)             found on LONEOS images

C/2001 K3 (Skiff)             found on LONEOS images

P/2001 R6 (LINEAR-Skiff)      reported by me as a comet, but prediscovery
                              LINEAR observations on two nights as an asteroid
                              that had already been linked by the MPC;
                              Jupiter-family comet

C/2001 S1 (Skiff)             found on LONEOS images

P/2002 S1 (Skiff)             found on LONEOS images; Jupiter-family comet

P/2004 A1 ( ? )               found on LONEOS images as stellar but with
                              unusual motion; identified as comet in follow-up
                              images taken immediately afterwards with Lowell
                              Perkins 1.8-m telescope.  Centaur-like orbit.

Jupiter-family comet   captured objects in roughly 3:2 resonance with Jupiter,
                       orbital periods of 7 to 9 years.  many of these are
                       perturbed inward from the Kuiper belt.
Saturn-family comet    captured objects in roughly 2:1 resonance with Saturn,
                       orbital periods of about 15 years.
hyperbolic orbit       comet that's being thrown out of the solar system,
                       mainly from perturbation by Jupiter.

So the number of comets found by me with no one else involved is six, and
maybe seven once the name for 2004 A1 is announced.  The first of these didn't
come until 1999, and 12 years separated it from Wiseman-Skiff.  (We didn't
do much survey-type asteroid observing between about 1990 and 1998,
so sure enough we didn't find any comets during that interval.)  Then there
are the hyphenated ones where I'm given top billing or where I'm the junior
partner, and ones where the names arguably should be reversed from what the
official name is.  I don't know how to count those, so I'll stick with the
six for the moment.
     There are in addition several 'LONEOS' comets (some of them hyphenated
as well), which were identified as comets after being reported by me as
asteroidal but with unusual motion.  These are similar to the case of 
Catalina-Skiff or LINEAR-Skiff, and are now fairly common with the many faint
comets found by the big surveys (LINEAR, NEAT, LONEOS).  Some (but not all)
of these hyphenated comets with the survey name given rather than the observer
can be regarded as failure to do our job as thoroughly as we might have.
My opinion is that those comets should be named for the person who identified
them as comets (and too bad for us), but that's not the way it works under the
current rules.
     The comet-naming scheme is utterly byzantine, and seems to depend
largely and mysteriously on Brian Marsden, who interprets the rules on a whim
and would like to omit the names altogether.  The rules have also changed over
the years.  After a few of these ambiguous cases, I've gotten so I don't care
any more.  The main thing is that the comet is picked up and made available
for study.

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